Several factors are involved in maintaining clean and efficient gas turbine engines. Such factors may include both preventive and non-preventative maintenance. Periodic engine cleaning is one such preventive maintenance practice that is recommended to minimize engine compressor and turbine contamination.
There are documented cases of one-time engine compressor wash improvements in Total Specific Fuel Consumption (TSFC) and Exhaust Gas Temperature (EGT) of 0.85% and 8° C., respectively. Additionally, cleaning an engine prior to contamination can be beneficial to engine performance. For example, a fleet TSFC improvement of 1.0% per year may be realized when performing engine cleanings every three months. Generally, the recommended engine cleaning interval is every 1000 to 1200 hours commencing after a heavy maintenance. In this regard, engine manufacturers have estimated a reduction of 1.0% TSFC and 10° C. EGT over a 6000 hour period with regular cleaning according to the recommended cleaning interval. Another benefit of cleaning an engine regularly is an ease in contamination removal at each wash.
An additional benefit of engine cleaning washes is the reduction of turbine sulphidation. Engine manufacturers' tests have shown that engine cleaning washes remove water soluble substances applied to the turbine. For example, a large domestic operator using engine cleaning washes at 100 to 150 hour intervals with expanded repair limits has been successful in reducing turbine blade scrap rate due to sulphidation damage at 6200 hours from 100% to less than 5%. It should be noted that engine cleaning for sulphidation reduction generally requires much shorter time intervals between washes than those used for regular compressor cleaning.